Connect a folding door with an armature without deforming the door panels
You could rig this sort of bus door arrangement without bones:

.. a series of hinges, each parented to the previous hinge.
Every hinge has its Z rotation driven by the zero'th, 'master' hinge.. ('Rot Master'). The odd-numbered hinges have -2 * the Z rotation of the master:

and the even-numbered hinges have +2 * the Z rotation of the master. The drivers can be cut-and-pasted; with care, pairs of doors can be duplicated along with their drivers.
The master's Z rotation is driven by the handle, thus:

.. where the '20' in the expression is the distance from the handle to the master when fully extended. The handle should have a Limit Location constraint to prevent it going off-axis, below 0, or beyond full extension.
The master and the handle can both be parented to a Root object (The big cube at the left) so the whole rig can be moved around. Doors, or whatever, can be parented to their respective hinges.

..sort of a cheap, limited, home-made IK.